Hi s7r83dg3, pieces that have surfaces that are heavily overlapping directly on top of each other tend to be difficult for the Booleans to handle.

The reason why is that the Booleans are mostly oriented around one object cutting another object, so they try to process pairs of surfaces and calculate the intersection curves where 2 surfaces intersect.

The problem is, when you have 2 surfaces going over largely the same surface area instead of clearly punching through each other, the intersection curve becomes much more difficult to calculate.

The Join command on the other hand only glues together surfaces where they are touching at unattached edges, it does not try to create intersections between things.

So that's why the approach that Steve is mentioning would help out for your situation here - you've got a lot of pieces that are touching each other, so rather than trying to use a Boolean you can instead delete some of the common faces that are overlapping one another, and then use the Join command to join the pieces that now have exposed edges that touch one another.

- Michael